2 - Qatar Health 2021 Conference abstracts
  • ISSN: 1999-7086
  • EISSN: 1999-7094


COVID-19 pandemic created an unprecedented demand for reagents and diagnostic tools to confirm COVID-19 cases. Thus, the development of a robust in-house diagnostic test is considered of high importance. Within a few days after exposure, the human body produces specific antibodies that recognize the surface proteins of the invading SARS-CoV-2 virus1. Therefore, virus specific immunoglobulins are neutralizing antibodies and their appearance in the blood is a good sign of immunity2. The aim of this study was to develop an in-house COVID-19 serology ELISA test to quantify induced antibody responses. This test can help identify convalescent plasma donors with high antibody titers that can be used to treat other patients. Spike protein antigen is highly expressed in SARS-CoV-23. Recombinant protein corresponding to the spike receptor-binding domain (RBD), which binds to specific antibodies circulating in COVID-19 patients’ blood was used as the antigen in this colorimetric ELISA test. Briefly, a 96-microtiter well plate was coated with RBD protein, where serum dilutions were added. Antibody titers were detected using an anti-human IgG- peroxidase labelled antibody and the substrate o-phenylenediamine dihydrochloride; measured at optical density (OD) of 450 nm (Figure 1). The in-house quantitative serology test was validated using serum samples collected from severe COVID-19 patients (n = 282) admitted to the intensive care unit at Hamad General Hospital. Serum samples from non-COVID-19 (n = 10) were used as a negative control. We detected high antibody titers in ~90% of COVID-19 sera. In contrast, no SARS-CoV-2 specific antibodies were detected in the serum of non-infected subjects (n = 6), pooled human serum collected before 2019, or Middle East Respiratory Syndrome (MERS) infected subjects (n = 3) confirming the specificity and the sensitivity of this in-house serology test. This in-house quantitative serology test is sensitive, specific, and inexpensive. The test can address the rising issue of COVID-19 supply chain globally and foster the capacity-building efforts envisioned by Qatar University.


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  • Article Type: Conference Abstract
Keyword(s): antibody titerCOVID-19ELISASARS-CoV2 and serology
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